Known in the art is a hydraulic vane machine (SU, A, 819363), comprising a casing accommodating a rotor having a cam-shaped end face and a shaft. The casing has slots receiving radially extending vanes mounted for axial movement under the action of springs. During rotation of the rotor by a drive motor, the vanes which are permanently pressed against the cam end face of the rotor reciprocate to ensure regular variation of capacity of pressure and suction working chambers. The vanes divide these chambers, and the volumetric efficiency, which is the ratio of the volume of utilized fluid to the maximum volume of the working chamber, depends on quality of sealing between the end faces of the vanes and the cam end face of the rotor. It is defficult to provide an efficient sealing member on the narrow end face of the vane. Accordingly, the volumetric efficiency of the machine is rather low.
Also known in the art is a rotary displacement pump (SU, A, 877129) having a casing with an inner spherical surface mating with the outer surface of vanes having power take off shafts provided thereon to extend along their axes of summetry at an angle with respect to each other.
There is also provided a partition extending in the diametrical plane having its outer surface mating with the inner surface of the casing. Vane supports and a sealing member received in a groove are provided in the diametrical plane of the partition. This machine has an increased volumetric efficiency because of an increase in the useful volume of the working chambers with the same inside diameter of the casing. However, the provision of a sealing member that takes a part of the useful space of the working chambers lowers the possibility of increasing the volumetric efficiency. In addition, the sealing line in the diametrical plane is long and very sinuous so that is very difficult to ensure a reliable sealing.